Effect of hypertonic solutions on the blood-brain barrier

The effect of hypertonic urea and saline on the blood-brain barrier of the dog was quantitatively measured by the indicator diffusion technique. Urea appeared to stimulate glucose transport into the brain, while the diffusionary loss of fructose was enhanced. Hypertonic saline affected the diffusionary loss of the test sugars in a similar manner, but had no effect on glucose transport. The blood-brain barrier alterations were not reversible, but did decrease somewhat with time.